Personal computers include a display monitor for displaying visual images produced as a result of processing of data in the personal computers. Until recent years, the display monitors provided an image of only graphics on the faces of the display monitors. Graphics may be defined as documents, or charts, in which the images displayed on the faces of the display monitors are static or stationary.
In recent years, graphics and video have been simultaneously displayed on the faces of the display monitors in personal computers. Video may be defined as images in which there is a dynamic motion of an animate or inanimate object. The video has been typically stored on a tape or in a VCR. Generally the video has been displayed in a window on the face of the display monitor and the graphics has been displayed on the face of the display monitor other than the window.
The graphics has been stored in a binary form representing each of the primary colors red, green and blue for a pixel. When the graphics representation has been in true colors, each pixel has been illustratively formed from first, second and third pluralities of binary bits respectively representing the primary colors red, green and blue, the number of binary bits in each of the first, second and third pluralities generally being the same. For example, each of the three (3) primary colors has been represented by eight binary bits.
Alternatively, the graphics representation for each pixel has been in pseudo color. In pseudo color, graphics pixel has been represented by a plurality (generally 8) of binary bits which have indicated a particular one of a plurality of different positions in a lookup table. At each position, pluralities of bits, arbitrarily selected, have represented the primary colors red, green and blue. For example, when the graphics pixel is represented by eight (8) binary bits, the lookup table has 256 different positions, each selected by an individual pattern of binary 1's and binary 0's in the eight (8) binary bits. The color selected from the lookup table is designated as pseudo color because the arbitrarily selected colors at the 256 positions in the lookup table are only a small number of the millions of possible colors which are available in the real world.
In the prior art, each video pixel has generally been in a YUV or YCrCb format. In these formats, Y indicates the hue or intensity of the image dot provided by the pixel on the face of the display monitor and Cr and Cb (or U and V) represent the quadrature components of the color or chrominance in the pixel. Pixels in the YUV or YCrCb format are often compressed; as on a tape or in a VCR before they are recorded. To display the video image in a window on the face of a display monitor in a personal computer, the video pixels are decompressed and are then converted from the YCrCb format (or the YUV format) to the RGB format corresponding to the format for the graphics pixels.
Sometimes the video pixels are interpolated (or enlarged) after they have been decompressed. The enlargement of the image is generally obtained by averaging the values of each successive pair of adjacent decompressed pixels in a coordinate direction and inserting this average value between the adjacent pixels in such successive pair. The enlargement has been often, but not always, been primarily provided in a single coordinate direction.
U.S. Pat. No. 5,406,306 issued to Jonathan I. Siann, Conrad M. Coffey and Jeffrey L. Easley on Apr. 11, 1995, and assigned of record to the assignee of record of this application discloses and claims a "System For, and Method of, Displaying Information From a Graphics Memory and a video Memory on a Display Monitor." In the system of the '306 patent, graphics in the RGB format and video in a compressed YUV or YCrCb format are stored in a single display memory. The compressed video is read from the display memory in the compressed YUV (or YCrCb) format, decompressed and converted to the RGB format.
In the system disclosed and claimed in U.S. Pat. No. 5,406,306, the decompressed video image in the RGB format may then be enlarged. The graphics image may then be displayed on all of the face of a display monitor except for a window and the enlarged video image may be displayed in the window on the face of the display monitor. However, only the video image is enlarged in U.S. Pat. No. 5,406,306 and only the enlarged video image is displayed in the window on the face of the display monitor in the patent.